A camshaft which is provided with a plurality of cams for actuating an intake/exhaust valve of an engine for an automobile, in an axial direction thereof, has been conventionally known. A sprocket which a chain for transmitting a power to the camshaft is to be wound around is mounted on the camshaft.
The conventional camshaft is held having its outer peripheral face directly supported by a plurality of sliding bearings which are fixed in a housing of the engine (refer to, for example, Patent Document 1).
However, in this case, there is such a problem that a high torque is likely to occur in the camshaft, because rotation sliding resistance is increased due to sliding friction.